SM 214a - Hypernatremia Flashcards
Hypertonic hypernatremia is recognized as a SNa above…
145 mEq/L
What two things can cause hypertonic hypernatremia (dehydration?)
- Salt intake
- Persistent H2O losses not replaced by H2O intake
If a patient has hypernatremia (Na+ >145) and ther urine osmolality is high, what is the cause?
Insensible losses or GI loses
+
Decreased H2O intake
What is the treatment for hypernatremia resulting from sweating, GI loss, or solute diuresis?
Need to replace Na+, K+, and H2O
Use 0.9% or 0.45% saline with potassium
Caution: Do not cause serum Na to fall too quickly!
What factors could impair H2O diuresis?
- ADH release
- -> Reabsorption of water
- Decreased renal solute load
- -> Decreased osmotic pressure in the tubule
- -> Increased H2O reabsorption
- Volume depletion
- -> Decreased filtration
What is the treatment for nephrogenic DI?
Low sodium, low protein diet
+
Thiazide diuretics
+
NSAIDS
How do you estimate the water deficit in a patient with hypernatremia?
Current TBW x ( [SNa ÷ 140] – 1)
- TBW in men is 0.6 * lean body weight (kg)
- TBW in women is 0.5 * lean body weight (kg)
- TBW in the elderly is 0.45 * lean body weight (kg)
What are the causes of polyuric hypertonic hypernatremia
(increased CefH2O)
- Solute diuresis
- Gluose (diabetics)
- Mannitol
- Urea
- Diuretics
- Pure H2O diuresis
- Central Diabetes Insipidus
- Nephrogenic Diabetes Insipidus
How much water do we lose from insensible losses?
How?
~500 ml/day/m2 or 800 ml/day for a 70 Kg person
- 60% is through the skin
- 40% through respiration
A diabetic with polyuria will be [hypo/hyper]kalemic
A diabetic with polyuria will be hypokalemic
- Increased glucose in the tubule
- -> Increased water in the tubule
- -> Increased salt in the tubuel
- -> Increased Na+ delivery to the collecting duct
- -> Increased Na+ reabsorption
- -> Increased K+ secretion
- -> Hypokalemia
